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the 18th World Congress The International Federation of Automatic Control, Milano (Italy), August 28 - September 2, 2011

Une des solutions pour diminuer les émissions polluantes émises par un moteur à combustion interne est de réinjecter une partie des gaz d’échappement (Exhaust Gas Recirculation, EGR) à l'admission. Cependant, dans le cas d’une dilution du mélange air-carburant trop importante, la combustion est plus instable voire ne pas s’entretenir. L’ajout d’une faible quantité d’hydrogène a le potentiel de contrer cet effet négatif de forte dilution. C’est dans ce contexte que ce travail de thèse est basé sur une étude détaillée des effets combinés de l’ajout de l’hydrogène et de la dilution dans un moteur à allumage commandé alimenté par du méthane ou de l’iso-octane. Dans la première partie de ce travail, le potentiel de l’ajout de l’hydrogène combiné à la dilution, en termes d’émissions polluantes et de rendement global du moteur, est montré. Dans la deuxième partie, afin de mieux comprendre l’effet de l’hydrogène et de la dilution dans un moteur à combustion interne et leurs influences sur les propriétés fondamentales de la combustion, la vitesse de combustion laminaire, paramètre fondamentale, a été déterminée expérimentalement pour des mélanges isooctane ou méthane avec de l’air contenant différents pourcentages d’hydrogène et de dilution. Des corrélations ont pu ainsi être formulées permettant d’estimer la vitesse fondamentale de combustion laminaire pour ces mélanges. Dans la dernière partie, l’utilisation de deux diagnostics optiques (la chemiluminescence de la flamme et la tomographie par plan laser du front de flamme couplé à la mesure de vitesse par vélocimétrie par imagerie de particules) a permis de quantifier l’effet de l’hydrogène et de la dilution sur la propagation de flamme turbulente dans un moteur à allumage commandé muni d’accès optiques. Nous avons ainsi montré que le la vitesse de combustion laminaire a un effet prépondérant, comparé au nombre de Lewis, sur la vitesse de combustion turbulente dans un moteur à allumage commandé. / Optimization of the intake air-fuel mixture composition is one way to reduce pollutant emissions in Spark-Ignition (SI) engines. This can be achieved by operating with a diluted mixture, i.e by recirculating the exhaust. There are however limitations on the level of dilution that can ensure the smooth running of SI engines since diluting the air-fuel mixture induces an increase in combustion duration and in cyclic variations which impair engine performance. Adding an amount of hydrogen to the fuel can extend the dilution and the lean engine operability limits, which is beneficial in reducing both emission levels and fuel consumption. The objective of this study is to investigate the combined effects of hydrogen addition and nitrogen dilution in an SI engine fuelled with iso-octane or methane. In the first part of this study, we proved that high values of indicated engine efficiency and low values of pollutant emissions can be achieved by combining hydrogen addition and diluted air-fuel mixtures in the case of SI engines. In the second part, we provided experimental values of laminar burning velocity for diluted methane or iso-octane/hydrogen/air mixtures for a better understanding of the hydrogen and dilution effects on the fundamental properties of laminar combustion. New correlations to estimate laminar burning speeds of these mixtures were also presented. In the last part, the effects of hydrogen addition, with and without nitrogen dilution, on the turbulent flame propagation were investigated in an optical SI engine fuelled with iso-octane or methane. This study was done by using two different experimental techniques (direct flame radiation visualization and laser tomography images with Particle Image Velocimetry). The main conclusion is that the laminar burning velocity, rather than the Lewis number, has the dominant effect on the turbulent burning velocity in an SI engine.

Depuis plusieurs années, la diminution des réserves de pétrole incite les différents pays à accroitre leur indépendance énergétique. De plus, diminuer l’impact environnemental de la voiture est devenu l’une des priorités de notre société. En ce sens, les normes Européennes anti-pollution sont devenues plus strictes, tandis que certains polluants sont pointés du doigt pour avoir un impact néfaste sur la santé et l’environnement. Pour répondre à cette double problématique, l’utilisation de biocarburants de type alcools dans les moteurs à allumage commandé est l’une des voies envisagées. Ce virage a déjà été entrepris à petite échelle par l’Union Européenne qui a tout d’abord autorisé l’ajout de 5%, puis de 10% d’éthanol dans l’essence. En plus de l’éthanol déjà commercialisé, le Biobutanol, biocarburant de seconde génération, apparait comme un candidat à fort potentiel pour une utilisation dans les moteurs à allumage commandé. L’objectif de ce travail de thèse est d’étudier le potentiel de l’utilisation de mélanges isooctane/butanol dans les moteurs à allumage commandé, en termes de performances et d’émissions polluantes. De plus, ces résultats sont comparés à ceux de mélanges isooctane/éthanol. Le dégagement de chaleur dans un moteur à allumage commandé est en partie piloté par la vitesse de combustion laminaire. Cette caractéristique a été étudiée de manière expérimentale et numérique pour différentes conditions initiales (pression et richesse) dans une enceinte à volume constant. Puis, une étude sur les premières étapes de la propagation de la combustion a été réalisée dans un moteur monocylindre à accès optique. Ces résultats en moteur ont été corrélés avec les informations laminaires. Enfin, les émissions de polluants réglementés et non-réglementés, ainsi que les performances ont été étudiées dans un moteur monocylindre à allumage commandé. Une baisse de la plupart de ces émissions a été observée avec l’ajout des deux alcools. / For the past few years, the oil stock decrease encourages the different countries to increase their energy independence. Moreover, reducing the environmental impact of transportation became one of the priorities of our society. In this way, European emissions standards are stricter while several pollutants have been identified to have a negative impact on health and the environment. To answer this double problem, the use of alcohols biofuels in spark-ignition engines is one the promising ways. The European Union have already taken a small step in that direction by allowing a maximum of 10% of ethanol into gasoline. As well as ethanol is already marketed, Biobutanol, a 2nd generation biofuel, appears as a serious candidate with a strong potential for a spark-ignition engines use. The objective of this dissertation is to study the potential of the iso-octane/butanol blends use in spark-ignition engines, in terms of performance and pollutants emissions. Moreover, these results are compared to isooctane/ethanol blends. The heat release in spark-ignition engine is piloted for a part by laminar burning velocity. This characteristic was studied experimentally and numerically for different initial conditions (pressure and equivalence ratio) in a constant volume bomb. Then, the early flame kernel growth was studied in a spark-ignition single cylinder engine equipped with optical accesses. Those results were correlated with the results on the laminar burning velocity. Finally, regulated and non-regulated pollutants emissions and engine performance were investigated in a spark-ignition single cylinder engine. A decrease of most pollutant emissions was observed with both alcohols addition.

Uma nova metodologia para a criação de mapas base de injeção eletrônica de combustível para motores de combustão interna de ignição a centelha é apresentada e seu comportamento é comparado com os resultados fornecidos pela metodologia MVEM. A partir da utilização de equacionamentos da literatura, é feita uma modelagem do ciclo ideal Otto para um motor genérico alternativo monocilíndrico de 500 cm³ de volume deslocado. É modelada também uma válvula do tipo borboleta genérica de 0,06 m³ de diâmetro que opera tanto em regime subsônico quanto sônico. A pressão à jusante da borboleta é calculada para aberturas de 5° a 88,64°. Os modelos são acoplados a partir da vazão mássica de ar admitida, que é o parâmetro principal, sendo programados e simulados usando o programa comercial EES. O mapa base de pressão por abertura de borboleta por rotação resultante mostra o detalhe de descontinuidade pelo uso das equações de vazão mássica juntamente com a imposta pelas equações de coeficiente de descarga, implicando na mudança brusca de valores de pressão calculados para a região de abertura menor que 20%. O mapa de vazão mássica de combustível por rotação e por abertura de borboleta para uma razão estequiométrica de 14,67 também é gerado. Nele é possível observar a demanda por vazão mássica de combustível para cada rotação e abertura da válvula borboleta mostrando o caminho a ser seguido pelo motor para que seja atingida a vazão mássica necessária para obter-se a relação ar/combustível desejada. A metodologia proposta gera mapas base de combustível para módulos de injeção eletrônica. Os resultados são apresentados na forma de gráficos. O modelo produz resultados satisfatórios, reproduzindo o comportamento da válvula borboleta, comparado com a literatura. / A new methodology for EMS base maps to the internal combustion spark ignition engines is presented. Its behavior is compared with results from the MVEM methodology. From the technical literature an ideal Otto cycle for a generic reciprocating single cylinder engine with 500 cm³ of displaced volume. Also, throttle valve with a diameter of 0.06 m of diameter operating in subsonic and sonic flow regime is modeled. The downstream pressure is calculated for throttle openings of 5° to 88.64°. The models are coupled using the engine air mass flow rate as the main parameter, being programmed and simulated using a commercial EES software. The base map of pressure versus throttle opening and engine speed shows the discontinuity detail imposed from the mass flow and discharge coefficient equations, resulting into a abrupt change of pressure values calculated for an opening region less than 20%. The fuel mass flow versus revolutions per minute versus throttle valve opening for stoichiometric air fuel ratio of 14.67 is also generated. In such map it is possible to show the fuel mass flow demand for each rotation and throttle opening showing the path to be followed by the engine to reach the mass air flow needed to reach the target air fuel ratio. This methodology generates base fuel maps for electronic fuel injection modules. The results are presented in graph forms. The model presents satisfactory results that reproduce the throttle valve behavior, compared to the literature.

Uma nova metodologia para a criação de mapas base de injeção eletrônica de combustível para motores de combustão interna de ignição a centelha é apresentada e seu comportamento é comparado com os resultados fornecidos pela metodologia MVEM. A partir da utilização de equacionamentos da literatura, é feita uma modelagem do ciclo ideal Otto para um motor genérico alternativo monocilíndrico de 500 cm³ de volume deslocado. É modelada também uma válvula do tipo borboleta genérica de 0,06 m³ de diâmetro que opera tanto em regime subsônico quanto sônico. A pressão à jusante da borboleta é calculada para aberturas de 5° a 88,64°. Os modelos são acoplados a partir da vazão mássica de ar admitida, que é o parâmetro principal, sendo programados e simulados usando o programa comercial EES. O mapa base de pressão por abertura de borboleta por rotação resultante mostra o detalhe de descontinuidade pelo uso das equações de vazão mássica juntamente com a imposta pelas equações de coeficiente de descarga, implicando na mudança brusca de valores de pressão calculados para a região de abertura menor que 20%. O mapa de vazão mássica de combustível por rotação e por abertura de borboleta para uma razão estequiométrica de 14,67 também é gerado. Nele é possível observar a demanda por vazão mássica de combustível para cada rotação e abertura da válvula borboleta mostrando o caminho a ser seguido pelo motor para que seja atingida a vazão mássica necessária para obter-se a relação ar/combustível desejada. A metodologia proposta gera mapas base de combustível para módulos de injeção eletrônica. Os resultados são apresentados na forma de gráficos. O modelo produz resultados satisfatórios, reproduzindo o comportamento da válvula borboleta, comparado com a literatura. / A new methodology for EMS base maps to the internal combustion spark ignition engines is presented. Its behavior is compared with results from the MVEM methodology. From the technical literature an ideal Otto cycle for a generic reciprocating single cylinder engine with 500 cm³ of displaced volume. Also, throttle valve with a diameter of 0.06 m of diameter operating in subsonic and sonic flow regime is modeled. The downstream pressure is calculated for throttle openings of 5° to 88.64°. The models are coupled using the engine air mass flow rate as the main parameter, being programmed and simulated using a commercial EES software. The base map of pressure versus throttle opening and engine speed shows the discontinuity detail imposed from the mass flow and discharge coefficient equations, resulting into a abrupt change of pressure values calculated for an opening region less than 20%. The fuel mass flow versus revolutions per minute versus throttle valve opening for stoichiometric air fuel ratio of 14.67 is also generated. In such map it is possible to show the fuel mass flow demand for each rotation and throttle opening showing the path to be followed by the engine to reach the mass air flow needed to reach the target air fuel ratio. This methodology generates base fuel maps for electronic fuel injection modules. The results are presented in graph forms. The model presents satisfactory results that reproduce the throttle valve behavior, compared to the literature.

Uma nova metodologia para a criação de mapas base de injeção eletrônica de combustível para motores de combustão interna de ignição a centelha é apresentada e seu comportamento é comparado com os resultados fornecidos pela metodologia MVEM. A partir da utilização de equacionamentos da literatura, é feita uma modelagem do ciclo ideal Otto para um motor genérico alternativo monocilíndrico de 500 cm³ de volume deslocado. É modelada também uma válvula do tipo borboleta genérica de 0,06 m³ de diâmetro que opera tanto em regime subsônico quanto sônico. A pressão à jusante da borboleta é calculada para aberturas de 5° a 88,64°. Os modelos são acoplados a partir da vazão mássica de ar admitida, que é o parâmetro principal, sendo programados e simulados usando o programa comercial EES. O mapa base de pressão por abertura de borboleta por rotação resultante mostra o detalhe de descontinuidade pelo uso das equações de vazão mássica juntamente com a imposta pelas equações de coeficiente de descarga, implicando na mudança brusca de valores de pressão calculados para a região de abertura menor que 20%. O mapa de vazão mássica de combustível por rotação e por abertura de borboleta para uma razão estequiométrica de 14,67 também é gerado. Nele é possível observar a demanda por vazão mássica de combustível para cada rotação e abertura da válvula borboleta mostrando o caminho a ser seguido pelo motor para que seja atingida a vazão mássica necessária para obter-se a relação ar/combustível desejada. A metodologia proposta gera mapas base de combustível para módulos de injeção eletrônica. Os resultados são apresentados na forma de gráficos. O modelo produz resultados satisfatórios, reproduzindo o comportamento da válvula borboleta, comparado com a literatura. / A new methodology for EMS base maps to the internal combustion spark ignition engines is presented. Its behavior is compared with results from the MVEM methodology. From the technical literature an ideal Otto cycle for a generic reciprocating single cylinder engine with 500 cm³ of displaced volume. Also, throttle valve with a diameter of 0.06 m of diameter operating in subsonic and sonic flow regime is modeled. The downstream pressure is calculated for throttle openings of 5° to 88.64°. The models are coupled using the engine air mass flow rate as the main parameter, being programmed and simulated using a commercial EES software. The base map of pressure versus throttle opening and engine speed shows the discontinuity detail imposed from the mass flow and discharge coefficient equations, resulting into a abrupt change of pressure values calculated for an opening region less than 20%. The fuel mass flow versus revolutions per minute versus throttle valve opening for stoichiometric air fuel ratio of 14.67 is also generated. In such map it is possible to show the fuel mass flow demand for each rotation and throttle opening showing the path to be followed by the engine to reach the mass air flow needed to reach the target air fuel ratio. This methodology generates base fuel maps for electronic fuel injection modules. The results are presented in graph forms. The model presents satisfactory results that reproduce the throttle valve behavior, compared to the literature.

Thesis deals with design of the experimental single-cylinder spark ignition engines for research purposes. The main purpose of this work is the design crankcase. Summary of possible constructions of spark ignition engines is included. Basic dimensions and 3-D design of the experimental engine resulted from the summary. The numerical analysis of proposed crankcase in ADAMS (MBS) and ANSYS (FEM) software environment is also part of the work. Generally, the proposed solution of the experimental engine was focused on the universality and simplicity of the design.

The main aim of this diploma thesis is to design two different types of air throttles in the intake manifold and compare their influence on a loss of dynamics of the flow of drawn air. The main purpose is to compare the mass flow for wholly opened air throttle. It deals with creating CDF model of intake manifold by using 3D scanner Atos and software Pro/Engineer WF5. During the work, the results of the CFD analysis were used for a real testing.

This master’s thesis deals with the design of the throttle body of the intake manifold of a spark-ignition engine with regards to minimizing throttle loses at full engine load. The first part of this thesis focuses on the elements of intake tract structure on contemporary combustion engine including their design solutions and the theory of flow. The thesis also describes the creation of the 3-D CAD model of intake manifold with a throttle body and the description of the CFD flow simulation with the evaluation of resul.